Radar assembly with rectangular waveguide to substrate integrated waveguide transition
A radar assembly includes a rectangular-waveguide (RWG) and a printed-circuit-board. The rectangular-waveguide (RWG) propagates electromagnetic energy in a transverse electric mode (TE10) and in a first direction. The printed-circuit-board includes a plurality of conductor-layers oriented parallel to each other. The printed-circuit-board defines a substrate-integrated-waveguide (SIW) that propagates the electromagnetic energy in a transverse electric mode (TE10) and in a second direction perpendicular to the first direction, and defines a transition that propagates the electromagnetic energy between the rectangular-wave-guide and the substrate-integrated-waveguide. The transition includes apertures defined by at least three of the plurality of conductor-layers.
1. A method of manufacturing a printed circuit board (PCB) configured for use in a radar assembly, the method comprising:
forming a bottom substrate integrated waveguide (SIW) conductive layer configured to interface with an antenna of the radar assembly;
forming a plurality of SIW dielectric layers interleaved with a plurality of SIW conductive layers on top of the bottom SIW conductive layer starting with a bottom SIW dielectric layer and ending with a top SIW dielectric layer, the SIW dielectric layers and the SIW conductive layers forming an SIW configured to propagate electromagnetic energy in a first direction that is parallel to a plane of the PCB; and
forming one or more waveguide transition conductive layers interleaved with one or more waveguide transition dielectric layers on top of the top SIW dielectric layer starting with a bottom waveguide transition conductive layer of the waveguide transition conductive layers and ending with a top waveguide transition conductive layer of the waveguide transition conductive layers, the waveguide transition conductive layers comprising respective apertures, an aperture of the top waveguide transition conductive layer configured to interface with a rectangular integrated waveguide that propagates the electromagnetic energy in a second direction that is perpendicular to the first direction and normal to the plane of the PCB, the waveguide transition conductive layers and the waveguide transition dielectric layers forming a transition configured to direct the electromagnetic energy between the SIW and the rectangular waveguide.
2. The method of claim 1 , wherein forming the conductive layers comprises using photo-etching techniques.
3. The method of claim 1 , wherein forming the waveguide transition conductive layers comprises forming at least three waveguide transition conductive layers.
4. The method of claim 1 , wherein forming the dielectric layers comprises forming the dielectric layers such that at least two of the dielectric layers have different thicknesses.
5. The method of claim 4 , wherein forming the waveguide transition dielectric layers comprises forming the waveguide transition dielectric layers such that the waveguide transition dielectric layers have similar thicknesses.
6. The method of claim 1 , wherein forming the SIW dielectric layers comprises forming a quantity of the SIW dielectric layers that is at least double a quantity of the waveguide transition dielectric layers.
7. The method of claim 1 , wherein forming the bottom conductive layer comprises forming a slot radiator configured to couple the electromagnetic energy from the SIW to the antenna.
8. The method of claim 1 , further comprising forming vias through the dielectric layers effective to electrically couple the conductive layers.
9. The method of claim 8 , wherein forming the vias comprises filling holes formed in the dielectric layers with a conductive material.
10. The method of claim 8 , wherein forming the vias comprises forming a plurality of the vias that form perimeter walls through the dielectric layers.
11. The method of claim 10 , wherein forming the vias further comprises forming another plurality of vias that form a short wall through the waveguide transition dielectric layers.
12. The method of claim 11 , wherein the short wall bisects the waveguide transition dielectric layers proximate the apertures.
13. The method of claim 1 , wherein forming the waveguide transition conductive layers comprises forming the apertures such that the apertures have different sizes.
14. A method of manufacturing a printed circuit board (PCB) configured for use in a radar assembly, the method comprising:
forming one or more waveguide transition dielectric layers interleaved with a plurality of waveguide transition conductive layers starting with a bottom waveguide transition conductive layer of the waveguide transition conductive layers and ending with a top waveguide transition conductive layer of the waveguide transition conductive layers, the waveguide transition conductive layers comprising respective apertures, the aperture of the bottom waveguide transition conductive layer configured to interface with a rectangular integrated waveguide of the radar assembly that propagates electromagnetic energy in a first direction that is normal to a plane of the PCB; and
forming a plurality of substrate integrated waveguide (SIW) dielectric layers interleaved with a plurality of SIW conductive layers on top of the top waveguide transition conductive layer starting with an SIW dielectric layer and ending with a top SIW conductive layer of the SIW conductive layers, the SIW dielectric layers and the SIW conductive layers forming an SIW configured to propagate electromagnetic energy in a second direction that is perpendicular to the first direction and parallel to a plane of the PCB, the top SIW conductive layer configured to interface with an antenna of the radar assembly.
15. The method of claim 14 , wherein the PCB is configured to automotive use.
16. The method of claim 14 , wherein forming the dielectric layers comprises forming the dielectric layers such that at least two of the dielectric layers have different thicknesses.
17. The method of claim 14 , wherein forming the waveguide transition conductive layers comprises forming the apertures such that the apertures have different sizes.
18. The method of claim 14 , wherein forming the top SIW conductive layer comprises forming a slot radiator configured to couple the electromagnetic energy from the SIW to the antenna.
19. The method of claim 14 , further comprising forming vias through the dielectric layers effective to electrically couple the conductive layers, wherein forming the vias comprises forming a plurality of the vias that form perimeter walls through the dielectric layers.
20. The method of claim 19 , wherein forming the vias further comprises forming another plurality of vias that form a short wall through the waveguide transition dielectric layers and that bisects the waveguide transition dielectric layers proximate the apertures.